98 CLASS I. TROPIOPODA. ORDER I. BIMUSCULOSA. 



covered with sharp spines or tubercles ; the margins of the valves are 

 crenulated, interclosing with each other. The hinge consists of two ob- 

 lique approximate teeth in each valve, closely interlocking with each 

 other ; and there are also two remote lateral teeth. The muscular im- 

 pression of the mantle is entire, and the ligament is external. 



We have selected the following five-and-twenty species of this beauti- 

 ful genus, in order that its varieties may be fully illustrated. 



Examples. 



PI. LXXIII. Fig. 1, 1* and 1**. 



Cardium cardissa, Linnaeus, Syst. Nat., p. 1121. Lamarck, Anim. 

 sans vert., new edit., vol. vi. p. 411. Enc. Meth., pi. 293. f. 3. 



PI. LXXIII. Fig. 2. 

 Cardium biangclatum, Broderip and Sowerby, Zool. Journ., iv. p. 36V. 



PI. LXXIII. Fig. 3. 

 Cardium elatum, Sowerby, Proceedings Zool. Soc, 1833, p. 84. 



PI. LXXIII. Fig. 4. 

 Cardium obovale, Sowerby, Proceedings Zool. Soc, 1833, p. 84. 



PL LXXIV. Fig. 5. 

 Cardium Cumingii, Sowerby, Proceedings Zool. Soc, 1833, p. 82. 



PI. LXXIV. Fig. 6. 



Cardium impolitum, Sowerby, Jun., Proceedings Zool. Soc, 1840, 

 p. 107. 



PI. LXXIV. Fig. 7. 

 Cardium punctulatum, Broderip and Sowerby, Zool. Journ., iv. p. 366. 



PI. LXXIV. Fig. 8. 

 Cardium consors, Sowerby, Proceedings Zool. Soc, 1833, p. 85. 



